I've been a CoreStates/First Union/Wachovia/Wells Farg customer for over 25 years. I used to get calls from this number whenever I was driving very long distances on vacation or making large purchases in rapid succession around Christmastime. They have unlocked my card for me in the past once I confirmed purchases.
For the people reporting they don't have a card with them, I strongly suggest that you check for identity theft. Someone may have opened a card in your name. Just because you didn't open a card doesn't mean it's impossible there's a card out there based on your name and identity. Take this seriously.
I only chose "Event Reminder" below because the "Event" was suspicious activity on my card.
Identified themselves as Wachovia, left a full blown message about the fact that they may have screwed up an ACH I requested, call them back at X number and ask for X person again. They were able to identify exact amounts, dates and reasons, so sounds fully legit. Checked with my bank, appears they have not messed it up, so wooohooo!